JPH09274062A - Leak detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate measuring errors caused by the fluctuation of a high- voltage DC power-supply voltage value by the floating capacitance of a vehicle. SOLUTION: Protecting resistors 4, 6, 5 and 7 and detecting resistors 10 and 11 are sequentially connected from both end sides of a high-voltage DC power supply 1, respectively, and the connecting parts of two detecting resistors 10 and 11 are earthed to a ground 17. At the same time, switches 8 and 9 are connected in parallel to two protecting resistors 6 and 7 on both sides of the detecting resistors 10 and 11, respectively. The opening and closing of these two switches 8 and 9 are controlled, and voltages Vs1 and Vs2 at both end parts of the detecting resistors 10 and 11 are measured. Thus, leak is judged by a leak detecting part 14. In the leak detecting part 14, a timer 14A, which waits the acceptance of data for specified time after the switching of the switches 8 and 9, is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earth leakage detecting device used in vehicles such as electric vehicles, trains, trolleybuses, etc., which are powered by direct current.

[0002]

2. Description of the Related Art FIG. 2 shows the structure of a conventional leakage detecting device of this type. In FIG. 2, 1 is a high-voltage DC power supply including a plurality of batteries separated from the vehicle body ground, 2 and 3 are positive terminals and negative terminals of the high-voltage DC power supply 1, 4, 5, 6, and 7 are large resistances. Protective resistors with values, 8 and 9 are switches that short-circuit / open both ends of the protective resistors 6 and 7, 10 and 11 are detection resistors, 12, 1
Reference numeral 3 is an amplifier, 14 is a leakage detecting unit, 15 is an output terminal for outputting a leakage determination, 16 is a dielectric breakdown resistance, and 17 is a vehicle body ground.

Next, the operation of the above conventional example will be described.
In Figure 2, the dielectric breakdown consists of multiple batteries
It is assumed that it is occurring in the high voltage DC power supply 1. This time
The resistance value of the insulation breakdown resistance of is
Voltage value V of DC power supply 1_MBolt to V₁Bolt and V_TwoBo
The points are divided by the lt. Here, the resistance of the protection resistors 4,
630kΩ value, protection resistor connected to switches 8 and 9
The resistance value of 6 and 7 is 640 kΩ, and the resistance value of the detection resistors 10 and 11 is
The resistance value is 10 kΩ, and the voltage across the detection resistor 10 is V _S1,detection
The voltage across resistor 11 is V_S2And Also, as below
Define the condition. (1) V_S1M, V_S2M: When switches 8 and 9 are open
V_S1And V_S2Detection voltage (2) V_S1P, V_S2P: Switch 8 is closed and switch 9 is
V when open_S1And V_S2Detection voltage (3) V_S1Q, V_S2Q: Switch 8 is open, switch 9 is
V when closed_S1And V_S2Detection voltage (4) P_DEF = V_S1P-V_S2P (5) Q_DEF = V_S1Q-V_S2Q (6) PQ_DEF= P_DEF−Q_DEF

Next, a method of detecting electric leakage will be described. Switch the switches 8 and 9 as follows to switch the detection resistor 1
The voltages V _S1 and V _S2 across 0 and 11 are measured. (A) Both switch 8 and switch 9 are open (b) Switch 8 is closed, switch 9 is open (c) Switch 8 is open, switch 9 is closed Voltage V across detection resistors 10 and 11 in these three cases from _S1, V _S2, the voltage value V _M of the high-voltage DC power source 1, R breakdown resistor 16, the voltage V ₂ of the breakdown point, and leakage current I is calculated from the following equation. (7) V _M = 2 ⁷ × V _S1M +2 ⁷ × V _S2M = 2 ⁶ × V _S1P +2 ⁷ × V _S2P = 2 ⁷ × V _S1Q +2 ⁶ × V _S2Q (8) R = 10 ⁴ × (V _M − 128PQ _DEF ) / 3PQ _DEF (9) V ₂ = 2V _M -3-2 ⁷ × P _DEF / 3-R × P _DEF / 10 ⁴ = V _M / 3-2 ⁷ × Q _DEF / 3-R × Q _DEF / 10 ⁴ (10) I = V ₁ / R or I = V ₂ / R The leakage current I may be selected by comparing V ₁ and V ₂ .

The leakage detection unit 14 controls the opening and closing of the switches 8 and 9 as described in (a) to (c) above, and detects the voltages V _S1 and V _S2 across the detection resistors 10 and 11 at that time. By calculating according to the equations (7) to (10) from the measured values, it is possible to obtain the high-voltage DC power supply voltage value, the insulation breakdown resistance value, the voltage at the breakdown point, and the leakage current. Output to the output terminal 15.

[0006]

However, in the above-mentioned conventional leakage detection device, for example, in the case of an electric vehicle, the high voltage DC power supply is represented as shown in FIG. In FIG. 3, 18
Is a high-voltage DC power supply including a plurality of batteries separated from the vehicle body ground, 19 and 20 are positive and negative terminals of the high-voltage DC power supply 1, 21 is a body ground, and 22, 23 and 24 are equivalent. Stray capacitance. As shown in FIG. 3, since the vehicle itself often has a stray capacitance, the states of the switches 8 and 9 connected to the detection resistors 10 and 11 are set to, for example, switch 8 from closed to open, and switch 9 to At the moment of switching from open to closed at the same time, the value should drop to V _S1 , but since the voltage before switching the state of the switch is held in the stray capacitance, accurate V is maintained until this holding is completely discharged. The value of _S1 cannot be read. Similarly, although the value of V _S2 should rise, it becomes impossible to read the accurate value of V _S2 until the stray capacitance is charged. For this reason, there is a problem that the conventional leakage detection device cannot accurately determine the leakage. During actual driving, the voltage value of the high-voltage DC power supply fluctuates drastically due to load fluctuations, noise of the load motor due to inverter control, and noise of the inverter used to create a power supply whose body is grounded from the high-voltage DC power supply. Due to the influence, the high-voltage DC power supply voltage viewed from the body ground fluctuates in a constant cycle, and there is also a problem that an accurate leakage determination cannot be performed.

The present invention solves such a conventional problem, and an object of the present invention is to provide a leakage detecting device capable of accurately determining leakage.

[0008]

In order to achieve the above object, the present invention comprises a timer means for providing a waiting time until the V _S1 and V _S2 data is fetched after the switch is switched, and is provided with a voltage fluctuation and a constant period. In order to avoid noise and to read data, the waiting time is changed within a certain range, and the data read with different switches are selected by the leakage detection unit. Therefore, according to the present invention, by providing the above configuration, it is possible to accurately detect the leakage, detect the leakage point, and calculate the voltage value of the high-voltage DC power supply even in the actual vehicle.

[0009]

The invention according to claim 1 of the present invention is such that a protection resistor and a detection resistor are sequentially connected from both ends of a high-voltage DC power supply, and a connection portion of two detection resistors is grounded. With 2 on each side of each sensing resistor
In a leakage detection device equipped with a leakage detection unit, in which a switch is connected in parallel to each of the two protection resistors, the opening and closing of these two switches are controlled, and the voltage at both ends of the detection resistor is measured to determine the leakage. The detection unit is provided with a timer unit that waits for the data to be taken in for a certain period of time after the switch is switched, and it is possible to accurately make the leakage determination.

The invention according to claim 2 of the present invention is characterized in that, in the earth leakage detection device according to claim 1, the time to wait for the data to be fetched is variable, and it is during actual traveling. Even if the high-voltage DC power supply voltage value fluctuates due to the fluctuation of the load, it can be dealt with.

According to a third aspect of the present invention, in the leakage detecting device according to the first or second aspect, one of the two switches is closed with the voltage value measured with the two switches opened as a reference value. When the voltage value measured in the above state does not fall within the setting error range with respect to the reference value, those data are invalidated, and the leakage determination can be performed more accurately.

According to a fourth aspect of the present invention, in the leakage detecting device according to any one of the first to third aspects, when the leakage is detected a plurality of times consecutively, it is determined that the leakage is the first time. This is a feature, and it is possible to more accurately determine the electric leakage.

(Embodiment) An embodiment of the present invention will be described below. The configuration of the leakage detecting device according to the present embodiment is almost the same as that of the conventional example shown in FIG. 2, except that the leakage detecting unit 14 is provided with a timer 14A and that the leakage detecting unit 14 is newly provided. Is that the function of is added. In FIG. 1, 1 is a high-voltage DC power supply composed of a plurality of batteries or the like separated from the vehicle body ground, 2 and 3 are positive and negative terminals of the high-voltage DC power supply 1, respectively, and 4, 5, 6, and 7 are large resistances. A protective resistance having a value, 8 and 9 are switches that short-circuit / release both ends of the protective resistances 6 and 7, 10 and 11 are detection resistances, 12 and 13 are amplifiers, 14 is a leakage detection unit, and 15 outputs a leakage judgment. An output terminal, 16 is a dielectric breakdown resistance, and 17 is a vehicle body ground. And 14A is a timer provided in the leakage detection unit 14.

Next, the operation in the present embodiment
explain. First of all, the switch status is that switches 8 and 9 are open.
At the time of V_S1MAnd V_S2MCapture the value of. Then
Switch 8 is closed and switch 9 is open.
Replace. After that, discharge from the stray capacitance of the vehicle and
Charging to the floating capacitance is over, set by timer 14A
The V_S1PAnd V_S2PVoltage value settles down to a constant value
After the waiting time until_S1PAnd V_S2PCapture
No. This waiting time is experimentally determined. After that,
Switch 8 switch to open and switch 9 to closed
I can. After that, similarly after the end of the waiting time, V_S1QAnd V
_S2QTake in. Switch the state of the switch in the same way
The standby time is reset each time
_S1And V _S2The value of is taken in.

As described above, according to the present embodiment, since the data is taken in after a lapse of a fixed time after the switch is switched, the measurement error due to the stray capacitance between the high voltage DC power supply of the vehicle and the body is eliminated. Can be lost,
Even in an actual vehicle, it is possible to accurately detect a high-voltage DC power supply voltage value, an electric leakage, and a dielectric breakdown point.

It should be noted that the standby time is made variable within a certain range, and is changed at each data fetching timing, so that the high-voltage DC power supply voltage value fluctuates due to load fluctuations during actual traveling. be able to.

The high-voltage DC power supply voltage value is shown in equation (7).
Is expressed by three equations,_S1MAnd V_S2M
V calculated using the value of_MUsing the value as the reference value, V_S1PAnd
And V _S2PV calculated using_MValue or V_S1Qand
V_S2QV calculated using_MValue is set to the reference value
If it does not fall within the error range, all these data are
Leakage caused by treating as invalid data and eliminating all
The determination can be made more accurately. Within the setting error range
If you enter, treat these data as valid data
High voltage DC power supply voltage value, dielectric breakdown resistance value, dielectric breakdown
Calculate the voltage value of the place.

Further, the leakage judgment can be made more accurately by determining the leakage only after the leakage judgment is repeated a plurality of times.

[0019]

According to the present invention, as is apparent from the above-mentioned embodiment, data is taken in after a lapse of a certain time after switching the switch, so that the stray capacitance between the high voltage DC power supply of the vehicle and the body is obtained. It is possible to eliminate the measurement error due to, and it is possible to accurately detect the voltage value of the high-voltage DC power supply, the leakage current, and the location of the dielectric breakdown even in the actual vehicle.

[Brief description of drawings]

FIG. 1 is a schematic circuit diagram of an earth leakage detection device according to an embodiment of the present invention.

FIG. 2 is a schematic circuit diagram of a leakage detection device in a conventional example.

[Fig. 3] Equivalent diagram of high-voltage DC power supply in actual vehicle

[Explanation of symbols]

 1 High voltage DC power supply 2 Positive terminal of high voltage DC power supply 3 Negative terminal of high voltage DC power supply 4, 5 Protection resistance 6, 7 Protection resistance 8, 9 Switch 10, 11 Detection resistance 12, 13 Amplifier 14 Earth leakage detector 14A Timer 15 Electric leakage judgment Output terminal 16 Dielectric breakdown resistance 17 Body ground

Claims (4)

[Claims] 1. A protection resistor and a detection resistor are sequentially connected from both ends of a high-voltage DC power supply to ground the connection portion of the two detection resistors to ground, and two protection resistors on both sides of each detection resistor are connected. In the leakage detection device including the leakage detection unit that connects the switches in parallel and controls the opening and closing of these two switches to measure the voltage across the detection resistor to determine the leakage, the leakage detection unit is An electric leakage detection device comprising timer means for waiting for data to be taken in for a certain period of time after switching the switch. 2. The earth leakage detection device according to claim 1, wherein a waiting time for capturing data is variable. 3. When the voltage value measured with the two switches opened is the reference value, and the voltage value measured with one of the switches closed is not within the setting error range with respect to the reference value. 3. The leakage detection device according to claim 1, wherein the data is invalidated. 4. The leak is first determined when the leak is detected a plurality of times in succession.
The leakage detection device according to any one of 1.